This application is based on application no. 266332 filed in Japan on Sep. 1, 2000, the content of which is incorporated hereinto by reference.
1. Technical Field
This invention relates to a photovoltaic device and a method of manufacturing the photovoltaic device.
2. Description of Related Art
A photovoltaic device shown in FIG. 12, which has been developed in advance by the applicant, has a photovoltaic module 200. In this photovoltaic module 200, generating areas A-D are electrically connected in series along their external peripheries. Each of the generating areas has a first electrode layer 20, a light-active semiconductor layer 30 and a transparent conducting layer 40 laminated on an insulating resin substrate 110 such as polyimid. The module 200 has protective resin films 181, 182 such as PET, which are mounted on top and back sides via adhesive layers 183, 184, respectively.
The output of the photovoltaic module 200 is led to output terminals 150a, 150d formed of materials such as conducting paste. The photovoltaic device has the protective resin film 182 having openings 185a, 185d, which lead to the output terminals 160a, 150d in the backside. The openings 185a, 185d are filled with conducting materials 152,152 such as conducting paste. The conducting materials 152,152 are disposed on the surface of the protective resin film 182 and on the periphery of the openings 185a, 185d. 
In the related photovoltaic device mentioned above, after completion of the device, it can occur that the outputs from the backside conducting materials 152 are nothing or low. Such a defect has been proved to be due to disconnection(s) inside of the conducting materials 152.
The reason for the disconnection is as follows. The conducting materials 152 are formed by heat-drying at approximately 150xc2x0 C., after patterning original material such as conducting paste with screen printing. The conducting paste as the original materials includes binder such as polyimide, phenolic or epoxy binder, and conducting powder such as silver, nickel, carbon or aluminum etc. The conducting materials 152 are disposed through materials having different thermal expansion, such as the substrate 110, the adhesive layer 184 and the protective resin film 182. Accordingly, in a heat-drying process, each of the materials expands, and when the materials cool back to room temperature, each of the materials contracts, so that the conducting materials 152 are subjected to stress. This stress makes the conducting materials 152 partially crack. The crack breaks the conductivity between the conducting powders and causes the conducting materials to become disconnected.
In addition, the conducting material can be subjected to stress due to expansion in a heating state under sunshine, and contraction in a low-temperature state in the night or the like, and thus the conducting materials 152 can disconnect even during operation.
This invention was developed to solve the above described types of problems, it is thus an object of the present invention to provide a photovoltaic device and a method of manufacturing the device, in which conducting materials for leading an output to the outside will.be less likely to become disconnected.
A photovoltaic device of the present invention comprises a photovoltaic module that is disposed on or above an insulating substrate, a conducting material electrically connected with an output terminal of the photovoltaic module and disposed on one facet side of the substrate, a protective layer covering the facet side of the photovoltaic module. The protective layer has opening positioned so as to face the conducting material, and the opening is larger than the shape of the facet side of the conducting material.
A method of manufacturing of a photovoltaic device of the present invention comprises a process step of forming a hole in an insulating substrate connected with an output terminal of a photovoltaic module formed on an insulating resin substrate, a process step of disposing a conducting material in a backside of the substrate to connect with the output terminal electrically via the hole, and a process step of forming a protective layer having an opening at a position facing the conducting material in the topside of the substrate, which is larger than the shape of backside of the conducting material.
In the photovoltaic device mentioned above, the photovoltaic device has the substrate and the protective layer, and even if the substrate and the protective layer are formed of materials having different thermal expansion, the conducting materials are disposed inside of the opening of the protective layer, so that expansion or to contraction of the protective layer does not stress the conducting materials when the expansion or contraction occurs during use of the photovoltaic device. Therefore the conducting materials are less likely to become disconnected.
In addition, in the method of manufacturing of the invention, the conducting materials are formed before the protective layer is formed. For example, when a conducting paste is used as the conducting material, printing and heat-drying are employed. The conducting material is formed before forming the protective layer, so that the problem of the related art device mentioned above does not occur. In the related art device, expansion or contraction of the protective resin film, such as the protective layer due to heating or forming the conducting materials, causes the conducting materials to become disconnected.
The above and further objects and features of the invention will more fully be apparent from the following detailed description taken in conjunction with the accompanying drawings.